Ion trap



G. J. MUCHER Nov. 13, 1951 ION TRAP Filed May 13, 1948 R 0 T A E V m 5g?f flay/per MM/CM Patented Nov. 13, 1951 ION TRAP GcOrgeJ, Mucher,Brooklyn, N. Y., assignorto Qlarostat Mtg, (20., 1110., Brooklyn, N. Y.,a cor-. ppration of New York Application May 13, 1948, Serial No. 26,765

10,-Claims. (Cl. 313-45) This invention relates to. electronicapparatus, and particularly to. apparatus for use, with cathode raytubes such as-used in television receiving systems.

Although the invention is: not: limited to the viewing tubes of.television systems, it has advantages particularly appropriate. for suchuse and will be described withrespect. thereto. The kinescope, which isthe electron tube. used for reproducing a television image at the:receiver, is a cathode ray tube in which. a. stream of electrons isdischarged by an electron gun. and is caused to traverse the viewingscreen at the enlarged end of the tube. The viewing screen-is offluorescent material which glows. atthepoint of impact of the electronstream thereon. Means are em-. ployed to focus the electron stream, andapparatus intermediate the. focusing means and thescreen causes theelectron stream to traverse the viewing screen and produce the image byvariation in the intensity of illumination of said screen.

It has been found most desirable to prevent the bombardment of theviewing screen by ions. Ions are many times heavier than electrons andvary widely in weight; their inertia is. greater than the power of the.deflection means to deflect them over the full area of the screen, andthe screen may thus be subjectedto a relatively small area ofbombardment which breaks; it. down aft.- er relatively short. use.

Magnetic devices are used to prevent the ions from reaching the screen.Some such devices comprise magnets of opposite polarity maintained insuitable spaced relationship about the neck of the kinescope.Thesemagnetic devices, which are known in the. art as. ion traps? areplaced suitably intermediate the electron gun and the focusing coil. Themagnet nearest the. electron guns is the stronger and deflects. the raytoward the side wall of the tube. The second magnet picks up, i. e.deflects, the, electrons, away from the wall of the tube and brings theminto the field of the focusing coil; the ions, being much heavier andpossessing, greater inertia, are not returned to the field. of the,focusing coil and are dissipated as heat at. the. wall Of. the tube.

Field conditions peculiar to each installation require that the poles ofthe magnets of the ion trap be adjusted relative. to. each other andthat the ion trap be, shifted axially of the tube to its point ofvgreatest efiectiveness. Once the adjustment is made it. should remainfixed until some. subsequent change. in operating conditions makes itnecessary to readlusteither the relation of the magnetic poles or theposition at the trap on the neck of the tube. This adjustment is made bythe service man, who may be mechani cally inept or careless, and who isusually working under adverse conditions. Some presently known iontraps, are supported on the tubes by means of rubber spacers or plateswhich rest directly on. the tube. Such plates are frequently soaffectedby the heat of the tube that they stick to the walls thereof and make itmost difllcult to remove the trap or to shift it along the neck of thetube. Other traps clamp to the tube .by screw clamps or the like and itis difficult to tighten or loosen the clamps to accomplish theadjustment or readjustment. With either type of trap, there is greatdanger-of breaking the tube while making the adjustment. A furthercomplication is inherent in the tube itself; the trade has standardizedon a tolerance of /8 in the diameter of the neck of the tube. Hence amass produced ion trap must embody some means of adjusting to the neckdiameter of a particular kinescope.

The present invention aims to provide an improved ion trap which may beeasily placed about the neck of the cathode raytube, which may be easilyadjusted for relative polarity position of the. respective magnets andwhich may easily be shifted axially along the neck of the tube.

It is therefore an object of the invention to provide an improvedmounting for the magnetic elements of an ion trap.

It is a further object of the invention to provide an ion trap whichresiliently embraces the wall of the electron tube for conformity to thediameter thereof, and which will remain in axially adjusted positionwithout the necessity of screw clamps or the like.

It is a further object of the invention to provide an ion trap which maybe readily passed over the tube base when necessary to install or removethe trap, without having to loosen or displace component parts oi thetrap for its mounting means.

Other features and advantages will hereinafter appear.

In the accompanying drawings,

Fig. 1 is a side elevation showing a portion of, the neck of anelectronic tube with my improved ion trap mounted thereon;

Fig. 2 is an end elevation of the trap, looking in the direction of thearrows 2-4 in Fig. 1.;

Figs. 3 and 4 are vertical sectional elevations. looking respectively inthe direction of the are rows 3-3 and 4-4 of Fig. 1; and

comprise no part of the present invention. It"

is to be understood, however, that within theneck of the tube there isprovided the usual electron gun (not shown) in which the electronbeam Yis developed and directed toward the target area or screen at the end ofthe tube. As is well known, the electron beam is focused and thendeflected to trace a pattern on the target screen.

The spring clips provide for easily shirting the device along the tubeneck, and grip said neck with sufiicient force to prevent accidentalmovement either axially or rotatably of the tube neck after adjustmenthas been made. There is no organic material in contact with the tubeneck to soften or disintegrate due to the operating 'terfiperature 'o'f"the'ftube. It will be .noted that" the minimum effective diameters ofthe ion trap are such that it may be easily slid over the tube baseduring the insertion or removal of the device. It is unnecessary,therefore, to remove or loosen any parts during such-insertion orremoval, and the possibility of tube breakage or damage during theremoval or adjustment of the trap is greatly reduced.

The focusing coil and the deflector means are located on or about theneck of the tube to the right of the ion trap as viewed in Fig. 1. Thefocusing means are'disposed intermediate the ion trap and the deflectingmeans.

The trap-comprises a non-magnetic sleeve II, which may be of brass orother suitable'material, projecting from one end of which are a suitableplurality, ears [2 having channels or'grooves l3. Formed either integralwith the sleeve or suitably affixed to the underside thereof, are springclips I 4 for resiliently supporting the sleeve on the neck of the tube.Said clips are so arranged that the sleeve II is parallel to the axis ofthe tube. As illustrated, the clips are affixed to the sleeve ll bymeans of s uitable non-magnetic rivets Hi. It will be noted that theends of the clips I4 nearest the baseB are shorter than their opposite'ends, so that if necessarythe trap Ill may be moved relatively close tothe end wall of' 'the tube base. The clips" are sufiiciently springableor resilient to adjust to'the tube neck diameters of from 1%" to 1 saiddiameters representing the standard minimum and maximum neck diametersfor kinescope tubes! The sleeve l I mounts two permanent magnets; Magnetl6 has a strength of from 43 to 50 gausses; theoretically it would bepreferable to make the magnet in one piece comprising an almost completecircle interupted only by a relatively short air gap at the poles. It iscommercially more expedient, however, to form the magnet of twosubstantially semi-circular half portions so arranged that the commonpoles are adjacent as indicated in the drawings.

Magnet I! has a strength of from 8 to I5 gausses and is preferably arigid wire of circular cross section uninterrupted except for the shortgap !8. The front magnet 11 is in reverse polarityarrangement withrespect to therear magnet Hi. The minimum diameter of magnet I! isslightly less than that of. a circle passing through the base of the.grooves [3,- so that the ears, I2 frictionally hold the magnet whilepermitting a forcible rotation thereof.

The magnet I5 is riveted to the sleeve H and is arranged at right'anglesto the axis of the sleeve. The magnet I l is secured only by frictionalengagement with the ears I 2 and is in substantial parallelism with themagnet IS. The magnet I! may be rotated about the sleeve I0 by placingthe end'of a screw driver, for example, within the space l8 and exertingthe necessary directional pressure against an end wall of the magnet;thus the pole positions of the magnet with respect to each other maybeeasily adjusted in the field.

til

Thus, among others, the several objects of the invention as afore notedare achieved. Obviously numerous changes in construction andrearrangement of the parts might be resorted 'to without departing fromthe spirit of the inven-" tion as defined by the claims.

I claim:

1. An ion trap comprising a sleeve of nonmagnetic material having aplurality of inor-' ganic, non-magnetic spring clip means forfrictionally securing said sleeve upon a tubular support in parallelismwith the axis thereof a permanent magnet secured about said sleeve atone end thereof; a plurality of springable ears projecting from saidsleeveat the opposite end thereof; and a second permanent magnetrotatably carried by said ears and extending about said sleevesubstantiallyin parallelism with said first-named magnet.

2. An ion trap' comprising a sleeve of nonmagnetic material; a pluralityof non-magnetic, inorganic resilient members extending from said sleevemember to resiliently secure said sleeve upon a tubular support inparallelism with the axis thereof, a plurality of spring membersextending axially from said sleeve at one end thereof, said springmembers each having a channel which collectively define a circle havinga diameter greater than the diameter of said tubular support andarranged in a plane perpendicular to the axis thereof; a ring-shapedmagnet carried by said spring members Within the channels thereof; and asecond ring-shaped magnet carried by said sleeve' and circumscribing thesame adjacent the opposite end thereof.

3. An ion trap comprising a sleeve of non-magnetic material; inorganicspring means for supportin said sleeve upon a tubular member in spacedrelationship therewith, and in substantial parallelism with the axisthereof; a magnet fixed about said sleeve adjacent-one end thereof, saidmagnet having an annular field substantially at right angles to the axisof said sleeve; a second magnet disposed about said sleeve adjacent theopposite end thereof, said second magnet also having an annular field insubstantial parallelism with the field of thefirst-named magnet; andmeans for securin said second magnet to said sleeve while permittingrotation of said magnet in a plane perpendicular to the axis of saidsleeve.

4. In an ion trap a mounting member for application to the neck of acathode ray tube, means providing a magnet-mounting surface forming apart of said member, supporting means extending inwardly of andsecuredto said mounting mem-' her to contact the surface of a tube andbear-- ing surfaces forminga part of said supporting.

76 means whereby said mounting member. may be shifted with respect tothe tube surface while mounted thereon.

5. In an ion trap a mountin member for application to the neck of acathode ray tube, means providing a magnet-mounting surface forming apart of said member, supporting means extending inwardly of and securedto said mountin member to contact the surface of a tube, ears exendingaxially of said member and providing a support for a second magnet andbearing surfaces forming a part of said inwardly extending supportingmeans whereby said mountin member may be shifted with respect to thetube surface while mounted thereon.

6. An ion trap including a sleeve of non-magnetic material to encirclethe neck of a tube, a permanent magnet mounted upon said sleeve adjacentone end of the same, ears extending axially of and beyond the oppositeend of said sleeve and a second permanent magnet supported by said ears.

'7. An ion trap including a sleeve of non-magnetic material to encirclethe neck of a tube, a permanent magnet mounted upon said sleeve adjacentone end of the same, ears extending axially of and beyond the oppositeend of said sleeve, a second permanent magnet supported by said ears andneck-engaging clips of resilient material secured to the inner sleeveface and extending in the direction of the sleeve axis.

8. A mounting for adjustably positioning and holding a ring-shapedmagnet around a glass tube, said mounting comprising a member ofnonmagnetic material having a larger inside diameter than the outsidediameter of the glass tube, the ring-shaped magnet being held inposition on the outside of said member by engagement therewith, aplurality of clips of non-magnetic resilient material disposed withinsaid member, and

means preventing relative movement of said clips 40 longitudinally andcircumferentially of said member but permitting individual movement ofeach clip radially relative to said member for adapting the mounting tovarious diameters of glass tubes and frictionally holding the mountingin adjusted position thereon.

9. A mounting according to claim 8 wherein said magnet has an air gapand its inside diameter is slightly less than the outside diameter ofsaid member, whereby the magnet is sprung over said member and theengagement therewith is increased by the resilience of said magnet.

10. A mounting accordin to claim 9 wherein said member has a groovearound its outer surface and said magnet is sprung into said groove.

GEORGE J. MUCHER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,102,421 Kuehni Dec. 14, 19372,181,850 Nicoll Nov. 28, 1939 2,188,579 Schlesinger Jan. 30, 19402,211,614 Bowie Aug. 13, 1940 2,274,586 Branson Feb. 24, 1942 2,431,113Glyptis et al. Nov. 18, 1947 2,456,474 Wainwright Dec. 14, 19482,455,977 Bocciarelli Dec. 14, 1948 2,460,609 Torsch Feb. 1, 19492,499,065 Heppner Feb. 28, 1950 2,513,929 Gethmann July 4, 19502,544,898 Obszarny et al. Mar. 13, 1951 2,552,342 Mucher May 8, 19512,553,792 Smith et al. May 22, 1951 FOREIGN PATENTS Number Country Date501,931 Great Britain Mar. 8, 1939

